1. Field of the invention
The present invention relates to a method of separating oil or bitumen from surfaces covered with same either to clean the surfaces, such as concrete or metal surfaces which have become oil contaminated, or to recover the oil or bitumen therefrom. The invention is particularly directed towards the recovery of oil and bitumen from bitumen covered tar sands and oil sands from oil wells.
2. Description of the Prior Art
Solvents and surface charge modifiers have been used to clean oily surfaces but the result often includes an oil/water emulsion which is undesirable. Also, such methods involve large amounts of water or other solvent where the surface area to be cleaned is large. If the substrate is in the form of a sand, as in the case of oil bearing sands, the grain size can be so small that the total extended surface area per unit volume is extremely large. If solvent soluble surfactants or other chemical aids are used, then the residual quantities in the wet sand residue can be sufficiently great as to seriously affect the process economics.